Gonads, Hormones of the Ovaries and testes, and placenta. Dayana Ayala, Anatomy & Physiology P.5 3 March 2014

Gonads: The female and male gonads produce sex hormones that are identical to those produced by the adrenal cortex cells. The main difference is the source and relative amounts produced.

Ovaries The female gonads, or ovaries, are paired, almond-shaped organs that are located in the pelvic cavity, and besides producing female sex cells (ova or eggs) they produce 2 groups of steroid hormones: estrogen & progesterone.

Testes Testes are also part of the male reproductive system, they are oval-shaped, just like the ovaries and are responsible for producing sperm and androgens, mainly testosterone, and are contained in a sac behind the penis.

Progesterone and Testosterone Progesterone is a hormone secreted by the female reproductive system, that works mainly to regulate our menstrual cycles, being produced in the ovaries, placenta and adrenal glands. This hormone is known to be responsible for the releasing of an egg every month, during ovulation, and is thought to be the hormone that stimulates development of the glands that produce milk during pregnancy. Testosterone is the main hormone in males and testosterone is notorious for its role in sexual function, in addition to helping build muscle mass, maintain bone density and regulate hair growth, during puberty it stimulates glands to produce acne, facial hair, deepens the voice, and most importantly stimulates growth of spermatogenic tissue in testicles, where this hormone is secreted. Low testosterone can have negative effects in men, including gynecomastia, which is the development of breasts in men.

Estrogen Estrogen is the name given to the group of hormones that primarily influence the female reproductive tract, in its development, function, & maturitarion. The 3 major hormones are estradiol, estrone, and estriol. It is believed that the egg follicle and interstitial cells in the ovaries are the actual production sites of estrogens in the female. Estrogen levels in the bloodstream seem to be highest during the egg-releasing period (ovulation) and after menstruation, when tissue called the corpus luteum replaces the empty egg follicle.

Estrogen in males Estrogen is found in small quantities in men. Estrogen is produced to aid the reproductive system, increase libido and aid the growth of sperm. If a man increases too much estrogen, the results can be negative.

Placenta Placenta is a temporary organ that connects the developing fetus to the mother, in the uterine wall that allows nutrient intake, waste elimination and gas exchange through the mother’s blood supply. It serves as an endocrine organ and its hormones include progestins, estrogens, protein hormones such as placental lactogens and the hormone relaxin. All of these help the mother and baby maintain hormonal balance throughout pregnancy. After childbirth, the placenta is expelled from the uterine lining through the cervix and this is during the third stage of labor.